Tuesday, 07 October, 2025
A US-Japanese trio has won the 2025 Nobel Prize in Medicine for groundbreaking research that revealed how the immune system is kept in check by so-called “security guards,” the Nobel jury announced on Monday.
The laureates — Mary E. Brunkow and Fred Ramsdell from the United States, and Shimon Sakaguchi from Japan — have made decisive contributions to understanding how the immune system functions and why most people do not develop serious autoimmune diseases.
Sakaguchi, a professor at the Immunology Frontier Research Centre in Osaka, told Swedish broadcaster Sveriges Radio, “It’s an honour for me. I’m looking forward to visiting Stockholm in December” to receive the award in person. The Nobel committee, however, was unable to reach the two US-based laureates immediately.
“If you hear this, call me,” joked Thomas Perlmann, head of the Nobel Assembly, during the press conference announcing the winners.
The three scientists were recognized for identifying regulatory T-cells, immune system “security guards” that maintain peripheral immune tolerance, preventing the body from attacking itself. Their discoveries have opened a new field of research and paved the way for potential treatments for autoimmune diseases, improved cancer therapies, and safer stem cell transplants, the Nobel jury said.
Key Discoveries
Sakaguchi made the first critical breakthrough in 1995, challenging the prevailing belief that immune tolerance only develops through the elimination of harmful cells in the thymus, a process known as central tolerance. He discovered a previously unknown class of immune cells that protect the body from autoimmune diseases.
Brunkow, senior project manager at the Institute for Systems Biology in Seattle, and Ramsdell, senior advisor at Sonoma Biotherapeutics in San Francisco, made a complementary discovery in 2001. They identified a gene called Foxp3 in mice, explaining why certain animals were particularly susceptible to autoimmune disorders. Mutations in the human equivalent of this gene were later shown to cause IPEX, a serious autoimmune disease.
In 2003, Sakaguchi linked these findings, completing the scientific picture that now underpins modern understanding of immune regulation.
The trio will receive a diploma, a gold medal, and $1.2 million, shared equally, at a formal ceremony in Stockholm on December 10.
US Dominance and Concerns
Historically, researchers from major US institutions dominate the Nobel science prizes, reflecting long-standing investment in basic science and academic freedom. However, recent budget cuts to US science programmes, including termination of 2,100 research grants totaling around $9.5 billion by the National Institutes of Health, have raised concerns about maintaining this lead.
Thomas Perlmann, secretary-general of the Nobel Prize committee, noted, “It is no coincidence that the US has by far the most Nobel laureates. But there is now a creeping sense of uncertainty about the US’ willingness to maintain its leading position in research.”
Meanwhile, former President Donald Trump has publicly expressed his desire to win the Peace Prize, though experts say his “America First” policies and unilateral style make him an unlikely contender. Oeivind Stenersen, a Nobel historian, described it as “completely unthinkable,” noting that Trump’s approach contrasts sharply with the multilateral cooperation ideals the prize represents.
Potential frontrunners for this year’s Peace Prize include Sudan’s Emergency Response Rooms (ERR), volunteer networks aiding people affected by war and famine, as well as media watchdogs like the Committee to Protect Journalists, Reporters Without Borders, and Yulia Navalnaya, widow of Kremlin critic Alexei Navalny.
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A US-Japanese trio has won the 2025 Nobel Prize in Medicine for groundbreaking research that revealed how the immune system is kept in check by so-called “security guards,” the Nobel jury announced on Monday.
The laureates — Mary E. Brunkow and Fred Ramsdell from the United States, and Shimon Sakaguchi from Japan — have made decisive contributions to understanding how the immune system functions and why most people do not develop serious autoimmune diseases.
Sakaguchi, a professor at the Immunology Frontier Research Centre in Osaka, told Swedish broadcaster Sveriges Radio, “It’s an honour for me. I’m looking forward to visiting Stockholm in December” to receive the award in person. The Nobel committee, however, was unable to reach the two US-based laureates immediately.
“If you hear this, call me,” joked Thomas Perlmann, head of the Nobel Assembly, during the press conference announcing the winners.
The three scientists were recognized for identifying regulatory T-cells, immune system “security guards” that maintain peripheral immune tolerance, preventing the body from attacking itself. Their discoveries have opened a new field of research and paved the way for potential treatments for autoimmune diseases, improved cancer therapies, and safer stem cell transplants, the Nobel jury said.
Key Discoveries
Sakaguchi made the first critical breakthrough in 1995, challenging the prevailing belief that immune tolerance only develops through the elimination of harmful cells in the thymus, a process known as central tolerance. He discovered a previously unknown class of immune cells that protect the body from autoimmune diseases.
Brunkow, senior project manager at the Institute for Systems Biology in Seattle, and Ramsdell, senior advisor at Sonoma Biotherapeutics in San Francisco, made a complementary discovery in 2001. They identified a gene called Foxp3 in mice, explaining why certain animals were particularly susceptible to autoimmune disorders. Mutations in the human equivalent of this gene were later shown to cause IPEX, a serious autoimmune disease.
In 2003, Sakaguchi linked these findings, completing the scientific picture that now underpins modern understanding of immune regulation.
The trio will receive a diploma, a gold medal, and $1.2 million, shared equally, at a formal ceremony in Stockholm on December 10.
US Dominance and Concerns
Historically, researchers from major US institutions dominate the Nobel science prizes, reflecting long-standing investment in basic science and academic freedom. However, recent budget cuts to US science programmes, including termination of 2,100 research grants totaling around $9.5 billion by the National Institutes of Health, have raised concerns about maintaining this lead.
Thomas Perlmann, secretary-general of the Nobel Prize committee, noted, “It is no coincidence that the US has by far the most Nobel laureates. But there is now a creeping sense of uncertainty about the US’ willingness to maintain its leading position in research.”
Meanwhile, former President Donald Trump has publicly expressed his desire to win the Peace Prize, though experts say his “America First” policies and unilateral style make him an unlikely contender. Oeivind Stenersen, a Nobel historian, described it as “completely unthinkable,” noting that Trump’s approach contrasts sharply with the multilateral cooperation ideals the prize represents.
Potential frontrunners for this year’s Peace Prize include Sudan’s Emergency Response Rooms (ERR), volunteer networks aiding people affected by war and famine, as well as media watchdogs like the Committee to Protect Journalists, Reporters Without Borders, and Yulia Navalnaya, widow of Kremlin critic Alexei Navalny.
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